Most large industrial plants, high rise office and residential buildings, airports, warehouse facilities, military installations, and educational institutions have sprinkler systems and fire pumps onsite which, in the event of a fire, provide large quantities of water for immediate response before offsite fire crews can reach the location of the fire. Typically, an internal combustion engine is installed in a pump house to drive a fire pump. The fire pump will draw its water from a municipal main, an onsite reservoir, or a storage tank. Fuel for the engine is stored adjacent to and dual redundant batteries are located within the pump house. The engine will have a cooling water jacket but being installed within a closed area the coolant is not routed through a radiator to be air cooled as in the case of a motor vehicle engine but, instead, is routed through a tube and shell heat exchanger where the coolant is in tubes that make a number of loops within the shell through which cooling water is circulating. The engine jacket coolant is normally an ethylene glycol/water mixture which gives the coolant a wide temperature range of operation without either boiling or freezing.
The cooling water for the shell side of the heat exchanger is normally tapped off the fire pump discharge and passes through a strainer, a pressure regulator, a water control solenoid valve, and an indicating manual valve before entering the heat exchanger. In a marine application the cooling water is sea water. Should a malfunction occur and the flow be interrupted, a manual bypass system is provided to respond to engine overheating which will be indicated at the fire control panel in the pump house for the fire pump installation. However, if there is a wiring or circuit board problem in the fire pump controller panel, a strainer stoppage, a solenoid valve malfunction, or any of a number of possible malfunctions in the primary or manual bypass system there are no further indicators or warnings after the bypass system has been opened until the fire pump control panel in the pump house displays an alarm light which says “engine overheat”. After the engine has overheated and run, only four to six minutes, which is enough time for the engine to destroy itself and then the “engine trouble” light comes on. In other words, the backup safety control is dependant on the integrity of the control panel and the immediate response by a qualified onsite maintenance person. If for some reason, and there can be many, the panel fails to function or if the manual bypass system is not manually activated it will not operate, very quickly then destructive overheating of the engine will occur.
There are two major reasons why such malfunctions causing an overheat situation are now more likely to occur. First, in today's world with pressure on reducing costs, unfortunately, one of the first places that costs are reduced is in maintenance and, particularly, in the maintenance of equipment that goes unnoticed until there is an emergency. Quite often, because of reduced staff, or, if no staff is available, it is difficult to ensure that the periodically required maintenance that should be performed for a fire system is actually done. Thus it happens that fire control panels, valves, wiring, test runs and indicators are not regularly inspected on the timely basis that they should. The second reason, which is connected to the first, is that in an emergency when the engine starts up and begins to run there is usually no one continuously monitoring the control panels in the pump house as the maintenance staff personnel, that may or may not be onsite, are usually thinly stretched and are attending to what will appear to be the more important aspects of the emergency. However, should the fire pump engine fail, not only is there no water to fight the fire, the sprinkler and other systems will be jeopardized also. Severe injuries, loss of life, and loss of assets can be the tragic result as well as down time and very expensive replacement costs of equipment.
Accordingly, it is a general object of the present invention to provide a practical, automatic, redundant backup system that is independent of the fire pump controller and that will ensure that an engine does not overheat and destroy itself.
In marine installations the power and propulsion systems are virtually always diesel engines. While the marine diesels are cooled in a manner similar to the above described installation with the engine jacket coolant being circulated through a tube and shell heat exchanger, the coolant water is raw sea water or lake water pumped directly into the heat exchange. However, marine installations need safety by-pass systems just as the land based application mentioned above and it is another object of the present invention to provide such a system for marine applications.
The foregoing and other objects of the present invention are achieved by my invention which is described in more detail below.